Runny Nose: Why It Happens and How to Stop It

What is the scientific name for a runny nose?

The medical term for a runny nose is rhinorrhea, from the Greek rhis (nose) and rhoia (flow). Related terms:

Common causes of a runny nose

Common cold and other viruses

The common cold is the most frequent cause. A clear, watery discharge starts first, then becomes thicker and white, yellow or green over a few days as immune cells collect in it, before clearing within 7 to 10 days. Flu and COVID-19 can start the same way.

Allergies

Allergic rhinitis causes a clear, watery runny nose with sneezing fits, an itchy nose, throat and eyes, and no fever. Seasonal allergies are triggered by pollen; year-round allergies by dust mites, pet dander, mold or cockroaches.

Non-allergic (vasomotor) rhinitis

Here the nose overreacts without allergy. Triggers include:

• cold, dry or windy air (skier's nose)
• spicy or hot foods (gustatory rhinitis)
• strong smells, perfume, smoke and pollution
• changes in temperature or humidity
• alcohol

It typically causes a clear, watery drip and is common in older adults.

Rebound congestion

Using decongestant nasal sprays for more than 3 days can cause rebound swelling and a runny or blocked nose. See rhinitis medicamentosa.

Sinusitis

Sinusitis causes thick discolored discharge with facial pressure, a blocked nose and reduced smell. Chronic sinusitis lasts more than 12 weeks and is often linked to nasal polyps.

Other causes

• Hormonal changes: pregnancy and hypothyroidism cause nasal congestion and drip.
• Medicines: some blood pressure medicines, erectile dysfunction medicines and aspirin or NSAIDs in sensitive people.
• Nasal polyps: soft growths causing chronic drip, blockage and reduced smell.
• Crying: tears drain into the nose.
• Object in the nose: in young children, a smelly discharge from one side.

Why does my nose run constantly?

A runny nose that never seems to stop is usually due to allergies, non-allergic rhinitis, chronic sinusitis, rebound from decongestant sprays, or a trigger in your environment such as dust or cold air. Older adults often develop a constant clear drip when eating or going outside. A doctor can help identify the cause, and allergy tests can confirm allergies.

Runny nose on one side

Most runny noses affect both sides. A one-sided discharge has a narrower list of causes:

• an object stuck in the nose (common in children)
• a deviated septum or nasal polyp
• sinusitis on one side
• rarely, a tumor (especially with blood-stained discharge and blockage)
• rarely, a cerebrospinal fluid leak: a clear, thin, salty-tasting drip from one side, worse when bending forward or straining, sometimes after head injury or surgery

What the color of mucus means

How to stop a runny nose

Home remedies

• Saline spray or rinse: washes out mucus and allergens; safe for all ages.
• Steam or a humidifier: helps thick mucus drain.
• Fluids: keep mucus thin.
• Blow gently, one nostril at a time.
• Avoid triggers: smoke, strong scents, cold air (cover your nose with a scarf).

Medicines

• Antihistamines: best for allergic runny nose. Non-drowsy options suit daytime; older sedating ones dry the nose more but cause drowsiness.
• Steroid nasal sprays: the most effective treatment for allergic and chronic rhinitis. They take several days to work fully.
• Ipratropium nasal spray: prescription spray that stops a watery drip, useful for non-allergic rhinitis and colds.
• Decongestant sprays: help a blocked nose but use for no more than 3 days.
• Oral decongestants: avoid with high blood pressure, heart disease or glaucoma.

Do not give cough and cold medicines to children under 6 without medical advice.

When to see a doctor

See a doctor if a runny nose lasts more than 10 days without improving, keeps coming back, affects one side only, is blood-stained, or comes with high fever, facial swelling or severe headache. Your doctor may examine the inside of your nose with a light or small camera, arrange allergy tests, or test the fluid for a CSF leak if that is suspected.

Frequently asked questions

What is the medical term for a runny nose?

The medical term is rhinorrhea. When a runny nose is part of a cold, doctors often call it coryza or describe "coryzal symptoms". Rhinitis means the nasal lining is inflamed, which usually causes rhinorrhea.

Why does my nose run when I eat?

This is gustatory rhinitis, a type of non-allergic rhinitis. Hot or spicy food stimulates nerves in the nose that switch on mucus glands, causing a clear, watery drip. It is harmless. An ipratropium nasal spray used before meals can help if it is bothersome.

How long does a runny nose last?

A runny nose from a cold usually lasts 7 to 10 days. Allergic runny noses last as long as you are exposed to the allergen. If yours lasts longer than 10 days without improving, or keeps returning, see a doctor.

Is a clear runny nose allergies or a cold?

Both can cause a clear runny nose. Allergies are more likely if you have itchy eyes and nose, sneezing fits, no fever, and symptoms that recur in certain seasons or places. A cold usually comes with a sore throat, the mucus thickens over a few days, and it clears within 10 days.

Can a runny nose be serious?

Rarely. A constant clear, salty drip from one side after a head injury or surgery could be a cerebrospinal fluid leak. A runny nose with high fever, stiff neck or swelling around the eye needs urgent care. Most runny noses are from colds or allergies.